Can someone advise me of equivalent commands in other Oses? [I should investigate Popen as well, so that the printing can happen in parallel.]

I'm hoping that I can just save the file to print (temporarily) with an '.txt' extension. Otherwise I'll have to investigate sending the lines of the file to the printer.

The output would be completely unformatted and there would be no preview option. As mentioned, it would just be a rough and ready print option. It would, however, be possible to just print the selection and perhaps to give an (approximate) page number or range.

If it helps, below is a version that works for Windows. You just need to:

Share your printer;Edit the code below to reflect your computer and printers' names;Assign 'print_default' to a key-binding. [This could be added to the File menu.]

It creates a file with extension '.txt' in your temporary folder, which is over-written if printed again.If you are sending to a PDF generator you will need to modify its properties to accept text input and (if possible) set some margins.

I can easily modify it to print the selection or a range of line-numbers, and perhaps add a date-stamp, etc. But I still need some assistance with non-Windows OSes